Diagnoses of Families and Genera 567 



Querquedula. Size very small. Bill about as long as head, nar- 

 row, but broader than in Nettion. Culmen rounding toward tip. 

 Breadth of nail about one-third the breadth of tip of bill. Lamellae 

 concealed. Speculum greenish. Blue on wing-coverts. Nape without 

 a crest. Two species are found in North America. 



Casarca. Size about that of Anas. Sides of bill nearly straight. 

 Culmen almost straight. Lamellae of bill distinctly exposed. Specu- 

 lum bright. Plumage striking. One species of genus is a rare strag- 

 gler to North America. 



Spatula. Bill much longer than head, narrow at base and very 

 wide at tip (twice as wide at tip as at base), the edges of upper 

 mandible hanging over the lower in the shape of a spoon, nail form- 

 ing a hook. Lamellae many and entirely exposed. Tail short and 

 pointed with sharply pointed feathers. Wing as in Querquedula. 

 The one species found in North America occurs throughout the 

 northern hemisphere. 



Dafila. Neck very long. Bill as in Mareca, about three times as 

 long as wide. Tail wedge-shaped, with sharply pointed feathers ; in 

 adult male two central feathers projecting far beyond the rest. 

 Speculum of male brilliant, of female dull. The one species found in 

 North America occurs throughout the northern hemisphere. 



Aix. Bill shorter than head, very high at base, depressed toward 

 tip. Nail very large and much curved. Lamellae few. Base of maxilla 

 extending on side of head nearly to eye. Male with a large crest of 

 silky feathers, female with a small crest. Tail feathers broad and 

 rounded at tip. One species found in North America. 

 Subfamily Fuligulinse. The Sea-ducks. Type: similar to the 

 Anatinte, but hind toe with a membranous lobe. Feet larger, and 

 legs placed farther back. Wing usually without metallic speculum. 



This family contains in North America thirteen genera and twenty- 

 four species, of which one is believed to be extinct. One genus only 

 occurs as a straggler, and another only reaches the coast of Texas 

 except as a wanderer. Like the Anatina, the males are birds of 

 handsome plumage, the females usually much plainer. They fre- 

 quent chiefly salt water, gathering sometimes in enormous flocks, 

 feeding largely on shellfish. As a result of this food their flesh is 

 not considered desirable. The genera Aythya and Erismatura feed 

 on vegetable substances, and their flesh is excellent. They greatly 

 excel the river-ducks in their ability to dive; but on the wing 

 their flight is less graceful, and they do not rise as easily from the 

 water. 



